1. Field of the Invention
This invention relates to improvements in valves and more particularly, but not by way of limitation, to a relief valve adapted for use with either liquids or gaseous fluids.
2. Description of the Prior Art.
Relief valves are frequently used in order to vent fluid pressure from a fluid vessel, or the like, in order to prevent damage due to the excessive pressure build up within the fluid vessel. The problems related to the handling of liquids are usually different than the problems encountered in the handling of gaseous fluids, and it is normally necessary to change the relief valve from a gas valve to a liquid valve in the event the medium within the vessel is changed from a liquid to a gas. The removal and installation of the relief valve is usually time consuming and costly in that the fluid system may have to be at least partially "shut down" in order to replace the valve. Many relief valves have been developed for the venting of excessive fluid pressures, or for safety purposes, such as shown in the Hilliard U.S. Pat. No. 950,533, issued Mar. 1, 1910, and entitled "Valve;" Hudson U.S. Pat. No. 2,111,473, issued Mar. 15, 1938, and entitled "Combination Air Discharge and Vacuum Valve;" Roth U.S. Pat. No. 2,470,372, issued May 17, 1949, and entitled "Ball Type Pressure Relief Valve;" Goddard U.S. Pat. No. 2,770,255, issued Nov. 13, 1951 and entitled "Dual-Range Safety Valve;" Baker et al U.S. Pat. No. 2,771,091, issued Nov. 20, 1956, and entitled "Drill Pipe Float Valve;" Frain et al U.S. Pat. No. 2,793,656, issued May 28, 1957, and entitled "Relief Valve;" Fennema et al U.S. Pat. No. 2,831,500, issued Apr. 22, 1958, and entitled "Combined Relief and Check Valve Construction;" Mason et al U.S. Pat. No. 2,884,952, issued May 5, 1959, and entitled "Line Hydraulic Pressure Relief Valve;" Biddle U.S. Pat. No. 2,935,990, issued May 10, 1960, and entitled "Air and Vapor Eliminator for Pipe Lines;" Stahlhuth U.S. Pat. No. 2,964,310, issued Dec. 13, 1960, and entitled "Spring Assembly for Relief Valve;" Raymond U.S. Pat. No. 2,969,084, issued Jan. 24, 1961, and entitled "Pressure Responsive Valve;" Joles U.S. Pat. No. 3,145,732, issued Aug. 25, 1964, and entitled "Hydraulic Pressure Relief Valve;" Gassman U.S. Pat. No. 3,316,252, issued May 2, 1967, and entitled "Pressure Modulating Hydraulic Control Valve;" Hansen U.S. Pat. No. 3,347,266, issued Oct. 17, 1967, and entitled "Spring Biased Relief Valve;" Johnson U.S. Pat. No. 3,565,108, issued Feb. 23, 1971, and entitled "Fluid Valve;" Calisher et al U.S. Pat. No. 3,674,061, issued July 4, 1972, and entitled "Liquid Transfer Apparatus with Pressure-sensitive Automatic Shut-Off Nozzle;" Van Der Koogh U.S. Pat. No. 3,860,026, issued Jan. 14, 1975, and entitled "Automatic Air Vent;" Drori U.S. Pat. No, 4,011,884, issued Mar. 15, 1977, and entitled "Liquid-Level Valving Device Particularly Useful as Automatic Relief Valve;" Drori U.S. Pat. No. 4,209,032, issued Jan. 24, 1980, and entitled "Air-Relief Valves;" and Green U.S. Pat. No. 4,325,398, issued Apr. 20, 1982, and entitled "Safety and Venting Valves for Fuel Tanks Carried on Vehicles." These devices, however, do not appear to satisfactorily solve the problems hereinbefore set forth.